Atmospheric-pressure electric corona is a phenomenon observed when an existing high potential electric field between two electrodes causes ionization of gas media in the vicinity of the electrodes. Atmospheric-pressure electric corona, which usually appears as a Blue-Pink plasma cloud, is considered a precursor to gap discharge and Van De Graaff type sparks if the electrostatic potential is elevated over a certain threshold.
Electric Corona's are usually observed in defective electric circuits or high voltage electric lines as an unstable, elongated and luminescent plasma cloud. Coronal onset under atmospheric pressure requires potential fields on the order of 10 to 100 KV between two well-defined electric nodes. Thus, in the absence of imposed electric field and well-defined nodes atmospheric pressure corona generation is rare.
The phenomena known as Saint Elmo's Fire offers one example of an electric corona. It has been observed at the tip of ship masts under stormy sea conditions. In these conditions, an electric corona can be generated between a ship's mast tip, offering a first well-defined node and highly charged clouds which can function as a second node and which can create an estimated potential electric field in the range of millions of volts.
Under controlled conditions, the underlying matter of corona generation—in the form of a stable plasma state of material—has numerous uses. Plasmas find application in the fields of metallurgy, spraying and coating, cleaning, etching, metal cutting and welding, lighting, and others. The corona producing approaches described herein create plasma which may be used in many of these existing fields. More importantly, the approaches described herein open entirely new field-based opportunities for commercial applications and research.